In the manufacture of semiconductor devices, fine processing by lithography using photoresists has been conventionally performed. The fine processing is a processing method including: forming a photoresist thin film on a semiconductor substrate such as a silicon wafer; irradiating the thin film with an active ray such as ultraviolet ray through a mask pattern having a semiconductor device pattern depicted therein; carrying out development; and etching the substrate with the obtained photoresist pattern as a protective film, thereby forming fine projections and depressions corresponding to the pattern, on the surface of the substrate. However, with the higher integration of semiconductor devices in recent years, an active ray to be used tends to have a shorter wavelength, namely, shift from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). Accordingly, the influence of reflection of the active ray on a semiconductor substrate has become a serious problem.
A film known as a hard mask containing metal elements, such as silicon and titanium, has been used as an underlayer film between a semiconductor substrate and a photoresist. In this case, the photoresist and the hard mask are significantly different in components, and the rates to remove these by dry etching are greatly dependent on the types of gas used for dry etching. Therefore, the appropriate selection of a gas type allows the hard mask to be removed by dry etching without a large reduction in the film thickness of the photoresist. Thus, in the manufacture of semiconductor devices in recent years, a resist underlayer film has been increasingly disposed between a semiconductor substrate and a photoresist to achieve various effects such as an anti-reflection effect. Compositions for photoresist underlayer films have been studied, but, because of the diversity of characteristics demanded of the compositions, development of novel materials for photoresist underlayer films has been desired.
An invention has been described which provides a silicon-containing resist underlayer film-forming composition containing a polysiloxane having an organic group having a hydroxy or carboxy group, in which the organic group is, for example, norbornene, which has an aliphatic polycyclic structure (refer to Patent Document 1).
An invention has been described which provides a silicon-containing resist underlayer film-forming composition containing a polysiloxane having an organic group having a hydroxy or carboxy group substituted by an acid unstable group, in which the organic group has an aliphatic polycyclic structure, for example, norbornene (refer to Patent Document 2).